STRUCTURAL STUDY OF SIO2-TIO2 SOL-GEL FILMS BY X-RAY-ABSORPTION AND PHOTOEMISSION SPECTROSCOPIES

Sol-gel derived silica-titania films, containing 0-30 mol% TiO2, were prepared by spin-coating and heat treated at temperatures up to 900 de grees C. They were studied by X-ray photoemission (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The number of o xygen atoms in Si-O-Ti and Ti-O-Ti bonds was found to vary from 0 to 2 5% as the TiO2, content increased from 0-30 mol%. The fraction of thes e oxygen atoms also increased with heat-treatment temperature, to 700 degrees C, for the 80SiO(2)-20TiO(2) base composition, showing a conti nuous increase in both Si-O-Ti hetero-condensation and Ti-O-Ti home-co ndensation bonding sequences. (C) 1997 Elsevier Science B.V.